I had little trouble installing mt2exa in Adobe Type Manager Deluxe 4.1 (ATM) under Windows XP SP2. Since an older version of mt2exa was already installed, the critical steps were:

1. In ATM, on the Add Fonts tab, Deactivate the existing MT2EXA from
the font set that included it. (This has the effect of not making it
immediately available.)

2. Then, still in the ATM Add Fonts tab, Remove that same MT2EXA from
that font set. (All this does is remove the shortcut to the font that
ATM puts into its own subdirectory of the Windows\Fonts directory.)

If that's all you do, you still won't be able to install the new version.

3. On the ATM Font List tab, Remove the item MT2EXA.

4. Move the old pfb and pfm outside the usual directory where ATM
puts actual PostScript files --in my case, d:\psfonts and
d:\psfonts\PFM; this is something one selects when setting up ATM. (Or
rename the two files so as to use some other extension.)

It may be that one can avoid step #3 by doing step #4 first.

Now one can add the new MT2EXE in the normal way via ATM. (This has the
effect of, first, copying the pfb and pfm to the usual directory where
ATM puts actual PostScript files; and second, putting a shortcut to the
font in the ATM subdirectory of Windows\Fonts.)

Next, I copied mt2exa.tfm to the directory within the yandy tree where I
have the other mt2 tfm's, in my case:

yandy\FONTS\TFM\NonText\tfm-mt2

I then ran through Y&Y TeX the file Test_latex.tex that came with the
MathTimePro2 fonts. No complaints during TeX'ing; no complaints during
viewing in DVIWindo -- and by showing there the font list and clicking
the MT2EXA entry I was able to highlight the instances of that font
within the displayed dvi; and no complaints during printing, whether
directly to my printer through DVIPSONE or through the Adobe PDF printer
driver.